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Fuel economy comparison of conventional drive trains series and parallel hybrid electric step vans

A hybrid electric vehicle (HEV) is a vehicle that combines a conventional propulsion system with an on-board rechargeable energy storage system to achieve better fuel economy than a conventional vehicle HEVs do not have limited ranges like battery electric vehicles, which use batteries charged by an external source. The different propulsion power systems may have common subsystems or components. The objective of this study is to compare the fuel economies of a conventional step van, a series hybrid electric step van (HESV), and a parallel HESV by calculating the fuel consumption using the ADVISOR software by NREL. We also showed the results of the vehicles in different driving cycles including the Central Business District bus cycles, the New York City Cycle, and the US EPA City and Highway cycles.     

Development of an intelligent CAE system for auto-body concept design

The concept design phase is a critical step in auto-body design, as it has a great effect on later design work. This paper describes the implementation of an auto-body structure design in the early stages of a new auto-body developing program. In order to reduce the long design period and analysis error that plagues traditional auto-body concept design, an intelligent CAE system has been successfully developed and implemented based on the UGS NX/API opening platform. This system, the so-called ACD-ICAE (Auto-body concept design-intelligent computer aided engineering) System that means concept design-intelligent computer aided engineering system, employs a fully parametrized template method to build the conceptual auto-body geometry model and FEM model quickly and easily. It also integrates auto-body modeling, analysis and optimization on only one CAD platform via a parametric variables database. Moreover, all parametric variables are shared and updated in different phases of the ACD-ICAE System. A wizard User Interface (UI) based on knowledge of auto-body engineering was developed and used in this system. The procedures implementing the functional diagram of the ACD-ICAE system are also provided. A typical example of a car body concept design with four doors shows that the ACD-ICAE system is efficient and accurate.     

Creating bus timetables with maximal synchronization

This paper addresses the problem of generating a timetable for a given network of buses so as to maximize their synchronization. It attempts to maximize the number of simultaneous bus arrivals at the connection (transfer) nodes of the network. Transit schedulers, taking into account the satisfaction and convenience of the system's users, appreciate the importance of creating a timetable with maximal synchronization, which enables the transfer of passengers from one route to another with minimum waiting time at the transfer nodes. In this paper, the problem is formulated as a mixed integer linear programming problem, and a heuristic algorithm is developed to solve the problem in polynomial time. The efficiency of this algorithm, compared to optimal solutions, is illustrated through a series of examples.     

Modeling,parameter estimation and nonlinear control of automotive electronic throttle using a Rapid-Control Prototyping technique

An electronic throttle consists of a DC motor, spur gears, a return spring, a position sensor, power electronics and an electronic control unit. Fast and precise position control of this electromechanical system is relatively difficult due to very high friction and the strong nonlinearity of the spring. Simple application of linear control, such as PID, fails. In this paper, two new controller structures suitable for different reference signal types are described. The key component of the position controller is the friction compensator based on either/both feedforward or feedback principles. The quality of the resulting behavior was measured using several criteria including the measure of control activity around the equilibrium position. The control activity directly influences the vibration, the noise and the wear of the servo system. The proposed controllers demonstrated superior behavior compared with other published structures.     

具有惯性表面的两层流体的柯西-泊松问题(英文)

This paper is concerned with the generation of waves due to initial disturbances at the upper surface of a two-layer fluid, as the upper layer is covered by an inertial surface and the lower layer extends infinitely downwards. The inertial surface is composed of thin but uniform distribution of non-interacting material. In the mathematical analysis, the Fourier and Laplace transform techniques have been utilized to obtain the depressions of the inertial surface and the interface in the form of infinite integrals. For initial disturbances concentrated at a point, the inertial surface depression and the interface depression are evaluated asymptotically for large time and distance by using the method of stationary phase. They are also depicted graphically for two types of initial disturbances and appropriate conclusions are made.     

Urea-SCR system optimization with various combinations of mixer types and decomposition pipe lengths

The demand for NO_x after-treatment system has increased dramatically due to the stricter NO_x emission regulations for diesel vehicles. The urea-SCR system is one of the NO_x after-treatment methods found to be quite effective to meet the regulation requirement enforced by various authorities including the Euro-6. In order to develop an effective urea-SCR system, it is critical to establish an even distribution of reductant over the catalyst surface since this favorable distribution can increase reduction reaction and in turn, improve NO_x conversion efficiencies. In the current study, a number of design variations of the urea-SCR system which included two mixer types and three decomposition pipe lengths, were evaluated systematically using CFD analysis and experimental measurements. The purpose of the CFD analysis was to estimate the distribution of reductant within the urea-SCR system with a specific configuration and the purpose of the engine emission test was to measure the amount of NO_x reduction, respectively. The results from the systematic analysis revealed the relation between the reductant distribution over the SCR and the performance of the NO_x reduction.     

The impact of weather conditions on bikeshare trips in Washington,DC

Bicycle usage can be affected by colder weather, precipitation, and excessive heat. The research presented here analyzes the effect of weather on the use of the Washington, DC, bikeshare system, exploiting a dataset of all trips made on the system. Hourly weather data, including temperature, rainfall, snow, wind, fog, and humidity levels are linked to hourly usage data. Statistical models linking both number of users and duration of use are estimated. Further, we evaluate trips from bikeshare stations within one quarter mile of Metro (subway) stations at times when Metro is operating. This allows us to determine whether Metro serves as a back-up option when weather conditions are unfavorable for bicycling. Results show that cold temperatures, rain, and high humidity levels reduce both the likelihood of using bikeshare and the duration of trips. Trips taken from bikeshare stations proximate to Metro stations are affected more by rain than trips not proximate to Metro stations and less likely when it is dark. This information is useful for understanding bicycling behavior and also for those planning bikeshare systems in other cities.